Lipid profiling of barley root in interaction with Fusarium macroconidia

Abstract

Fusarium is the major causal agent of Fusarium head blight (FHB) in several cereal crops. Macroconidia, the asexual form of Fusarium, can infect the roots and aerial parts of plants. The response of cereal to attacks by Fusarium has been investigated at transcriptomic and metabolomic level, but there are no reports of root lipidomic assays carried out during Fusarium-root interaction. In order to determine how root phospholipids contribute to that interaction, we performed a lipidomics-based ESI-MS/MS assay coupled with a statistical analysis. It was found that phospholipid and galactolipid levels were not modified during early pathogen response, although some individual phospholipid molecular species did undergo significant changes. In plants exposed to macroconidia there was a rapid and transient increase in the phosphatidylcholine (36:4-PC) molecular species, in comparison with the control. By contrast, there was a decrease in lysophosphatidylcholine (16:0-, 18:2- and 18:3-LPC) levels. Furthermore, a phospholipase assay and the measurement of endogenous phytohormone levels through the use of fluorescent lipids and liquid chromatography-tandem mass spectrometry, revealed an increase in phospholipase A (PLA) activity, as well as in the endogenous amounts of Jasmonic acid (JA) and Salicylic acid (SA). The results indicate that barley root is able to modulate the glycerolipid fatty acid composition during the early response to Fusarium, suggesting a particular pathogen-sensing mechanism that could be useful to understand the role of lipids in plant-pathogen interactions